Understanding Power Anomalies in Mediation Analysis

Previous studies have found some puzzling power anomalies related to testing the indirect effect of a mediator. The power for the indirect effect stagnates and even declines as the size of the indirect effect increases. Furthermore, the power for the indirect effect can be much higher than the power for the total effect in a model where there is no direct effect and therefore the indirect effect is of the same magnitude as the total effect. In the presence of direct effect, the power for the indirect effect is often much higher than the power for the direct effect even when these two effects are of the same magnitude. In this study, the limiting distributions of related statistics and their non-centralities are derived. Computer simulations are conducted to demonstrate their validity. These theoretical results are used to explain the observed anomalies.     

心理学视野下的社会变迁研究：研究设计与分析方法

近年来,社会变迁导致的文化、心理与行为变化及其相互建构已经成为心理学的研究热点。社会变迁研究通常涉及和变迁相关的时间效应、时代效应以及和变迁无关的年龄效应。在考察变迁趋势及其影响因素时,常用的研究设计有跨时间比较、跨代际比较、跨地区比较(历史重构)等方法;常用的分析方法有传统的相关和回归分析和现代的时间序列分析(比如交叉滞后相关和格兰杰因果检验)等。由于每一种设计都有其优点和不足,在具体研究中,研究者要根据研究的问题和可操作性选择合适的方法;如果可能,最好同时采用多种方法,以寻求基于不同方法的聚合证据。     

消费决策中的零：零价格效应和零比较效应

数字“0”由于自身所具有的特性(最小的自然数和不可作为被除数),当其与商品的价格维度和属性维度相结合时会对消费者的决策产生影响。已有研究表明商品的零价格和零属性会对消费决策产生影响,即零价格效应和零比较效应。情绪和社会规范是零价格效应产生的心理机制,参照依赖则是零比较效应产生的心理机制。商品价格、商品类型和消费者的心理因素是零价格效应的边界条件;而选项的数量是零比较效应的边界条件。未来的研究可以从不同商品类型、不同社会规范、“价格-损失”与“价格-质量”、注意等角度对零价格效应进行深入研究;也可以从结构匹配模型和齐当别模型的角度进一步探索零比较效应的“比较”机制;可以探讨价格是否能被视为商品的“坏属性”,进而讨论零价格效应和零比较效应二者之间的关系。     

Standardized or simple effect size: What should be reported?

It is regarded as best practice for psychologists to report effect size when disseminating quantitative research findings. Reporting of effect size in the psychological literature is patchy – though this may be changing – and when reported it is far from clear that appropriate effect size statistics are employed. This paper considers the practice of reporting point estimates of standardized effect size and explores factors such as reliability, range restriction and differences in design that distort standardized effect size unless suitable corrections are employed. For most purposes simple (unstandardized) effect size is more robust and versatile than standardized effect size. Guidelines for deciding what effect size metric to use and how to report it are outlined. Foremost among these are: (i) a preference for simple effect size over standardized effect size, and (ii) the use of confidence intervals to indicate a plausible range of values the effect might take. Deciding on the appropriate effect size statistic to report always requires careful thought and should be influenced by the goals of the researcher, the context of the research and the potential needs of readers.     

锚定效应的产生前提及作用机制

为了探讨锚定效应的产生前提以及基础锚定效应的理论解释,设计了两个实验。实验一选取高、低、无三种锚值,设置了15ms、45ms、75ms、1000ms四种呈现时间,结果发现只有15ms条件下未出现锚定效应,随着呈现时间增加,锚定效应不断增大,低锚下的锚定效应高于高锚下的锚定效应。实验二设置了语意相同但表述形式不同的两种水平的锚值,结果发现两者引发的锚定效应不同。锚定效应的产生前提是注意,数字启动假说可以更好地解释基础锚定效应。     

视觉运动Simon效应和认知Simon效应的影响因素及机制

Simon效应是指与反应要求无关的刺激位置和反应位置在同侧时, 个体反应更快更准确的现象。对于Simon效应的产生机制, 大多数研究者认为, 在不同实验情境中获得的Simon效应有共同的产生机制。但是, 越来越多的证据显示, 在刺激形式、排列方式、刺激—反应规则以及反应方式等因素的影响下, 存在两种不同性质的Simon效应, 即视觉运动Simon效应和认知Simon效应。视觉运动Simon效应源于刺激位置自动激活其同侧反应所产生的影响, 认知Simon效应源于转译生成的编码间的相互干扰, 两者分别与背侧通路和腹侧通路的加工有关。     

On effect size

The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension, measure/index, and value), outline 10 corollaries that follow from our definition, and review ideal qualities of effect sizes. Our definition of effect size is general and subsumes many existing definitions of effect size. We define effect size as a quantitative reflection of the magnitude of some phenomenon that is used for the purpose of addressing a question of interest. Our definition of effect size is purposely more inclusive than the way many have defined and conceptualized effect size, and it is unique with regard to linking effect size to a question of interest. Additionally, we review some important developments in the effect size literature and discuss the importance of accompanying an effect size with an interval estimate that acknowledges the uncertainty with which the population value of the effect size has been estimated. We hope that this article will facilitate discussion and improve the practice of reporting and interpreting effect sizes.     

The Mystery of the Mozart Effect: Failure to Replicate

The Mozart effect is the purported increase in spatial-reasoning performance immediately after exposure to a Mozart piano sonata. Several laboratories have been unable to confirm the existence of the effect despite two positive reports from the original laboratory. The authors of the original studies have provided a list of key procedural components to produce the effect. This experiment attempted to produce a Mozart effect by following those procedural instructions and replicating the procedure of one of the original positive reports. The experiment failed to produce either a statistically significant Mozart effect or an effect size suggesting practical significance. This general lack of effect is consistent with previous work by other investigators. We conclude that there is little evidence to support basing intellectual intervention programs on the existence of the Mozart effect.     

The impact of processing time on the bizarreness and orthographic distinctiveness effects

The bizarreness effect and the orthographic distinctiveness effect (OD effect) are typical cases of secondary-distinctiveness-based effects. This study tested the simple attentional account or processing time hypothesis as a possible explanation of the bizarreness effect and the OD effect. In the bizarreness effect literature, this hypothesis gained support by some studies but was also discredited by other research. In light of these conflicting results, Experiment 1 was devised to test the processing time hypothesis in the bizarreness effect by using black-and-white concrete images and manipulating the time allotted for processing the stimuli (500 ms, 1000 ms, 3000 ms). Concerning the OD effect, no research has directly investigated the impact of processing time by examining the effect under varying amounts of study time. Experiment 2 was thus devised to investigate this same hypothesis in the OD effect and time allotted for processing the stimuli was manipulated (250 ms, 500 ms, 1000 ms, 3000 ms). Results did not support the processing time hypothesis since the magnitude of the bizarreness effect and of the OD effect was not modulated by the amount of time allotted for processing the stimuli. We refer to alternative explanations to account for these two secondary-distinctiveness-based effects.     

Inverting the Simon effect by intention

Summary The Simon effect indicates that choice reactions can be performed more quickly if the response corresponds spatially to the stimulus - even when stimulus location is irrelevant to the task. Two experiments tested an intentional approach to the Simon effect that assigns a critical role to the cognitively represented action goal (i. e., the intended action effect). It was assumed that the direction of the Simon effect depends on stimulus-goal correspondence, that is, that responses are faster with spatial correspondence of stimulus and intended action effect. Experiment 1 confirmed that the direction of the Simon effect was determined by spatial correspondence of stimulus and intended action effect, the latter having been manipulated by different instructions. Experiment 2 indicated that effects of correspondences unrelated to the action goal (i. e., stimulus to hand location or to anatomical mapping of the hand), contributed additively to the resulting Simon effect. It is discussed how current approaches to the Simon effect can be elaborated to account for these results.     

Movements or targets: What makes an action in action–effect learning?

According to ideomotor theory, actions become linked to the sensory feedback they contingently produce, so that anticipating the feedback automatically evokes the action it typically results from. Numerous recent studies have provided evidence in favour of such action–effect learning but left an important issue unresolved. It remains unspecified to what extent action–effect learning is based on associating effect-representations to representations of the performed movements or to representations of the targets at which the behaviour aimed at. Two experiments were designed to clarify this issue. In an acquisition phase, participants learned the contingency between key presses and effect tones. In a following test phase, key–effect and movement–effect relations were orthogonally assessed by changing the hand–key mapping for one half of the participants. Experiment 1 showed precedence for target–effect over movement–effect learning in a forced-choice RT task. In Experiment 2, target–effect learning was also shown to influence the outcome of response selection in a free-choice task. Altogether, the data indicate that both movement–effect and target–effect associations contribute to the formation of action–effect linkages—provided that movements and targets are likewise contingently related to the effects.     

Temporal Doppler Effect and Future Orientation: Adaptive Function and Moderating Conditions

The objectives of this study were to examine whether the temporal Doppler effect exists in different time intervals and whether certain individual and environmental factors act as moderators of the effect. Using hierarchical linear modeling, we examined the existence of the temporal Doppler effect and the moderating effect of future orientation among 139 university students (Study 1), and then the moderating conditions of the temporal Doppler effect using two independent samples of 143 and 147 university students (Studies 2 and 3). Results indicated that the temporal Doppler effect existed in all of our studies, and that future orientation moderated the temporal Doppler effect. Further, time interval perception mediated the relationship between future orientation and the motivation to cope at long time intervals. Finally, positive affect was found to enhance the temporal Doppler effect, whereas control deprivation did not influence the effect. The temporal Doppler effect is moderated by the personality trait of future orientation and by the situational variable of experimentally manipulated positive affect. We have identified personality and environmental processes that could enhance the temporal Doppler effect, which could be valuable in cases where attention to a future task is necessary.     

Dissociating object-based and space-based affordances

In what we term the orientation effect, faster spatial responses are made to the corresponding task irrelevant orientation of an object. We ask how this effect relates to object affordances, how attention may be involved, and how the effect relates to the better understood Simon effect. Two separate stimulus-response compatibility effects (an orientation effect and a Simon effect) were observed when spatial responses were made to photographs of objects whose orientation and location had been simultaneously manipulated. When attentional demands were high these separate effects were found using hand responses and foot responses, suggesting an abstract rather than specific coding of object affordances. However, when attentional demands were low only the Simon effect was observed, suggesting that, in order to obtain the orientation effect, objects must be represented at the level of an object.     

A sequential analysis of relevant and irrelevant information in the Stroop task

The effect of repeating relevant (colour) and irrelevant (word) stimulus information is investigated in two Stroop tasks. Thomas (1977) observed that the Stroop effect is reduced when the irrelevant word is repeated from trial n -1 to trial n. A similar effect was observed in the Simon task (Notebaert, Soetens, & Melis, 2001; Notebaert & Soetens, 2003a). MacLeod (1991) interprets this effect as sustained suppression and relates it to negative priming. In this paper we investigate whether the reduced Stroop effect for word repetitions is indeed related to the negative priming effect. In Experiment 1 with a response-stimulus interval (RSI) of 50 ms, the Stroop effect is not influenced by the sequence of the word and there is no negative priming effect. In Experiment 2 with an RSI of 200 ms, the Stroop effect is reduced for word repetitions but there is still no negative priming effect. This does not support the sustained-suppression hypothesis. The reduced Stroop effect for word repetitions is explained in terms of response priming.     

Interaction between mode of learning and subjective experience: Translation effects in long-term memory

It has been suggested that writing auditorily presented words at encoding involves distinctive translation processes between visual and auditory domains, leading to the formation of distinctive memory traces at retrieval. This translation effect leads to higher levels of recognition than the writing of visually presented words, a non-translation effect. The present research investigated whether writing and the other translation effect of vocalisation (vocalising visually presented words) would be present in tests of recall, recognition memory and whether these effects are based on the subjective experience of remembering or knowing. Experiment 1 found a translation effect in the auditory domain in recall, as the translation effect of writing yielded higher recall than both non-translation effects of vocalisation and silently hearing. Experiment 2 found a translation effect in the visual domain in recognition, as the translation effect of vocalisation yielded higher recognition than both non-translation effects of writing and silently reading. This translation effect was attributable to the subjective experience of remembering rather than knowing. The present research therefore demonstrates the beneficial effect of translation in both recall and recognition, with the effect of vocalisation in recognition being based on rich episodic remembering.     

图形面积判断任务下信息加工模式和信息呈现方式对吸引效应的影响

研究使用图形面积判断任务取代典型的双属性决策框架, 考察了不同信息加工模式和信息呈现方式对吸引效应的影响。实验1比较了不同信息加工模式对吸引效应的影响, 结果发现, 当被试以直觉的信息加工方式进行面积比较判断时, 吸引效应不显著, 而以分析的信息加工方式判断时吸引效应明显存在, 后者效应强度显著大于前者。实验2通过调整图形排列顺序, 比较了刺激材料呈现方式对吸引效应的影响, 结果表明, 被试以直觉的信息加工方式进行判断时吸引效应依然存在, 但其表现要受信息呈现方式影响, 相对于将目标图形放置于诱引图形和竞争图形之间, 将诱引图形放置于目标图形和竞争图形之间而成为判断背景时, 吸引效应强度更大。研究提出了吸引效应形成的两阶段理论, 认为吸引效应产生的根源同时来自直觉的和分析的两个信息加工阶段, 研究也证实信息呈现方式对被试信息加工方式造成较大影响, 进而影响吸引效应强度。     

Dissociation of the distance effect and size effect in one-digit numbers

Magnitude comparison of single digits is robustly characterized by a distance effect (close numbers are more difficult to compare than numbers further apart) and a size effect (for a given distance, comparison difficulty increases with increasing size). The distance effect indicates access to the mental number line (Dehaene, 1997), and the size effect is usually interpreted as indicating that the mental number line represents larger numbers more vaguely than smaller ones. In contrast, we have argued earlier (Verguts, Fias, & Stevens, 2005) that for symbolic numbers (Arabic or verbal notation), the size effect does not originate from the mental number line but, instead, originates from mappings to relevant output components that are specific for magnitude comparison. If the latter is true, it should be possible to dissociate the distance effect from the size effect in tasks other than magnitude comparison. In two experiments, we observed a robust distance effect insame/different judgments, which implies access to the mental number line. Yet the size effect was absent. Consistent with our prediction, this finding establishes a dissociation between the size effect and the distance effect.     

情绪对信任的影响:来自元分析的证据

采用元分析方法探讨情绪对信任的影响。通过中英文献检索,共有21篇文章70个独立样本符合元分析标准（N=4745）。其中积极情绪对信任的影响有47个独立样本,消极情绪对信任的影响有23个独立样本。元分析的结果表明,相对于中性情绪,积极情绪对信任起到一定的促进作用,呈中等效应量（d=0.49）;消极情绪对信任起到一定的抑制作用,呈较小效应量（d=-0.23）。调节效应检验发现,情绪的诱发方式、信任对象熟悉性以及信任测量方式的调节作用均不显著。     

Effect size measures for mediation models: quantitative strategies for communicating indirect effects

The statistical analysis of mediation effects has become an indispensable tool for helping scientists investigate processes thought to be causal. Yet, in spite of many recent advances in the estimation and testing of mediation effects, little attention has been given to methods for communicating effect size and the practical importance of those effect sizes. Our goals in this article are to (a) outline some general desiderata for effect size measures, (b) describe current methods of expressing effect size and practical importance for mediation, (c) use the desiderata to evaluate these methods, and (d) develop new methods to communicate effect size in the context of mediation analysis. The first new effect size index we describe is a residual-based index that quantifies the amount of variance explained in both the mediator and the outcome. The second new effect size index quantifies the indirect effect as the proportion of the maximum possible indirect effect that could have been obtained, given the scales of the variables involved. We supplement our discussion by offering easy-to-use R tools for the numerical and visual communication of effect size for mediation effects.